Method for Vertically Grounding and Leading Down from Inner Side of Composite Pole Tower and Pole Tower Thereof

ABSTRACT

A method for vertically grounding and leading down form an inner side of a composite pole tower and pole tower thereof, wherein the method includes the following steps: extending an upper metal cross arm from an extended line of at least one side of a ground wire cross arm which is made of metal, vertically leading down a ground down-leading wire from a distal end of the upper metal cross arm, connecting the ground down-leading wire to the pole tower via a lower metal cross arm at a distance under a lower lead, and grounding the ground down-leading wire along a tower body of the pole tower, wherein when an lower portion of the tower body is a metal pipe, the ground down-leading wire is selectively directly connected to the metal pipe via the lower metal cross arm. The upper metal cross arm and the lower cross arm are able to provide a distance between the ground down-leading wire and the pole tower. The method enhances the ability of bearing lightning flashover, increases the insulating intensity to lightning impact, and prevents burning to composite insulator by power-flow current after lightning flash over. And also the method is easy and simple for application.

NOTICE OF COPYRIGHT

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to any reproduction by anyone of the patent disclosure, as it appears in the United States Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention is in a field related to application of electricity transmission technology of an electric power system. And more particularly, the present invention relates to a method for vertically grounding and leading down form an inner side of a composite pole tower and pole tower thereof,

2. Description of Related Arts

Pole towers are important instruments in an electric transmission line. The property of material of pole powers has a direct influence on safety, economy, and reliability of operation of the electric transmission line. Since raw steel material has a high intensity and good weight ratio, pole powers of high voltage electric transmission line at home and abroad are mostly made of raw steel material. However, pole powers of raw steel material also have disadvantages such as being massive (density of the raw steel material is high) and easy to corrupt. And thus a lot of manpower and materials are required for construction, transport and maintenance of the pole towers. With the development of the composite materials, advantages such as light weight, high intensity, corrosion-resistant, bearable in high temperature and low temperature, durable, and good insulating property have been found in composite materials. Therefore, poles powers of composite material, which have advantages such as low cost of transporting (especially in a sparsely populated area), antifouling, corrosion-resistant and the like, have good utilication prospects. It should be noted that pole towers of composite material have already been widely used in some areas in Canada and America.

However, lightning protection is not an issue when the pole towers of composite material are used in Canada and America. The mainly reason is that these areas using pole towers of composite material do not suffered a lot from lightning (For these areas in Canada and America have long winters, and lightning days are very few). Furthermore, the electric transmission lines are of low voltage which is mostly lower than 110 kv and do not required grounding. In addition, influence of lightning on the system is not vital because the voltage is relatively low.

Recently, pole towers in China are made of reinforced concrete, wood or raw steel (a pole tower in the rank of high voltage which is more than 110 kv often is made of raw steel). Because of the outstanding property of composite material, many regions in China also begins to use composite material (for pole towers in the rank of high voltage which are more than 110 kv). However, in these regions of China, issues such as much efforts have been put on building the transmission corridor, lightning takes place frequently, and contamination should be concerned, so that when the pole towers of composite material are employed to these regions, focus should be put on reducing a width of the transmission corridor (reduce the maximum distance between the leads of the transmission line), avoiding damage by lightning (reduce the possibility of destroy by lightning), and preventing contamination (reduce the possibility of running out of order because of pollution flashover by increasing a climbing distance of the pollution flashover).

In order to prevent the pole towers from damage by lightning, ground wires should be installed to the transmission line (the pole towers in Canada and America have not been provided with ground wires because it is not a issue in these regions of these countries). The pole towers of composite material should be grounded to release lightning energy of the ground wires (lightning conductor) or tower peak during lightning so as to increase ability lightning protection of the pole towers.

Therefore, in a region in which lightning takes place frequently, grounding should be carefully taken in consideration when pole towers of composite material are applied in use (since the body itself of a steel pole tower is a metal conductor, ground wires are directly electrically connected to the earth through the body of the pole tower, so that grounding is not an issue for a steel pole tower). There are several kinds of grounding and leading-down methods which directly have influence on performance of lightning protection, reducing the width of the transmission line and contamination prevention, so that methods of grounding and leading-down are important and key issues that should be solved when the pole towers of composite material are in application.

SUMMARY OF THE PRESENT INVENTION

A main object of the present invention is to provide a method for vertically grounding and leading down form an inner side of a composite pole tower and pole tower thereof, so that advantage of the insulating property of the composite material of the pole towers is realized, and the present invention further has advantages such as reducing the width of transmission corridor and preventing damage by lightning and contamination by pollution flashover

Additional advantages and features of the invention will become apparent from the description which follows, and may be realized by means of the instrumentalities and combinations particular point out in the appended claims.

According to the present invention, the foregoing and other objects and advantages are attained by a method for vertically grounding and leading down form an inner side of a composite pole tower, wherein the method comprises the following steps: extend an upper metal cross arm from an extended line of at least one side of a ground wire cross arm which is made of metal and is positioned on top of the pole tower, vertically lead down a ground down-leading wire from a distal end of the upper metal cross arm, connect the ground down-leading wire to the pole tower via a lower metal cross arm at a distance under a lower lead, ground the ground down-leading wire along a tower body of the pole tower, wherein when an lower portion of the tower body is a metal pipe, the ground down-leading wire is selectively directly connected to the metal pipe via the lower metal cross arm.

Preferably, in the above method, symmetrically extend two upper metal cross arms from two sides of the ground wire cross arm respectively in a direction along a current lead thereof, and vertically and symmetrically lead down two ground down-leading wires.

Preferably, in the above method, the ground down-leading wires and the tower body are supported therebetween by at least an insulating arm, so that the ground down-leading wires are not easy to bend nor deform.

In accordance with another aspect of the invention, the present invention provides a composite pole tower which grounds from an inner side thereof, the pole tower comprises a tower body, a ground wire cross arm, an upper metal cross arm extended from an extended line of at least one side of the ground wire cross arm, a ground down-leading wire vertically extended from a distal end of the upper metal cross arm, a lower metal cross arm, wherein the ground down-leading wire is connected to the pole tower via the lower metal cross arm at a distance under a lower current lead of the pole tower, wherein the ground down-leading wire is grounded along the tower body of the pole tower, wherein when an lower portion of the tower body is a metal pipe, the ground down-leading wire is selectively directly connected to the metal pipe via the lower metal cross arm.

Preferably, two upper metal cross arms are symmetrically extended from two sides of the ground wire cross arm respectively in a direction along a current lead thereof, and two ground down-leading wires are then vertically and symmetrically leaded down.

Preferably, the ground down-leading wires and the tower body are supported therebetween by at least an insulating arm.

The present invention has following advantages.

Firstly, preventing the ground down-leading wire from short-circuiting with the tower body of the composite pole tower, so that advantage of the insulating property of the composite material of the pole towers is realized, and distance of the current lead climbing from the earth is increased, so that the ability of avoiding influence of pollution flashover is enhanced.

Secondly, avoiding adverse effect to insulating intensity by cross arm metal member during lightning, so as to make sure that the minimum space distance between the current lead and the earth is determined by the minimum distance of the current lead and the ground down-leading wire, so that insulating distance between the current lead and the earth is increased, so that insulating intensity for bearing impact of lightning is enhanced.

Thirdly, preventing burning to the composite insulator by power-flow current after lightning flash over.

Fourthly, the ground down-leading wires are not pulled out to be at a position above surface of the earth, so that inconvenience to daily life of people is prevented.

Fifthly, the structure is simple and easy to achieve.

Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.

These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a pole tower using unilateral ground down-leading wire according to a first preferred embodiment of the present invention.

FIG. 2 is a front view of a pole tower using bilateral ground down-leading wire according to a second preferred embodiment of the present invention.

FIG. 3 is an enlarged top view of the pole tower according to the above first preferred embodiment of the present invention.

FIG. 4 is a top view of the pole tower according to the above first preferred embodiment of the present invention.

FIG. 5 is a top view of the pole tower according to the above second preferred embodiment of the present invention.

FIG. 6 is a sectional view of the pole tower according to the above first preferred embodiment of the present invention.

FIG. 7 is a sectional view of the pole tower according to the above first preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is disclosed to enable any person skilled in the art to make and use the present invention. Preferable embodiments are provided in the following description only as examples and modifications will be apparent to those skilled in the art. The general principles defined in the following description would be applied to other embodiments, alternatives, modifications, equivalents, and applications without departing from the spirit and scope of the present invention.

Illustration of the symbols: 1-ground wire cross arm, 2-upper metal cross arm, 3-ground down-leading wire, 4-lower metal cross arm, 5-supporting insulating arm, 6-composite insulator, 7-cross arm metal member, 8-body of tower head, 9-ground wire, 10-upper phase lead, 11-middle phase lead, 12-lower phase lead,, 13-lower portion of tower body.

According to a first preferred embodiment of the present invention, A ground wire cross arm 1 of the pole tower is made of metal, wherein an upper metal cross arm 2 of a length D₁ is extended from a center of the ground wire cross arm 1 in a direction along the lead. A ground down-leading wire 3 is vertically extended from a distal end of the upper metal cross arm 2. The ground down-leading wire 3 is connected to the pole tower via a lower metal cross arm 4 at a distance D₂ under a lower current lead 12 of the pole tower. By providing the upper metal cross arm 2 and the lower metal cross arm 4, a predetermined distance D₁ is defined between the ground down-leading wire 3 and a body of tower head 8, so that short-circuiting between the ground down-leading wire 3 and the body of tower head 8 is prevented. And thus advantage of the insulating property of the composite material of the pole towers is realized, and distance of the current lead climbing from the earth is increased, so that the ability of avoiding influence of pollution flashover is enhanced. In addition, when D₁ is large enough, route of lighting flash over cannot reach the cross arm metal member 7 (route of lighting flash over is the minimum space distance between the ground down-leading wire and the lead, which is AB or A′B′, but not ACDEF nor A′C′D′E′F′, as shown in FIG. 3), so that adverse effect to insulating intensity by cross arm metal member 7 during lightning is also avoided (the adverse effect is that with the existence of cross arm metal member 7, when the ground down-leading wire is adhered to an outer surface of the pole tower, the minimum space distance between the ground down-leading wire and the current lead will be DE or D′E′ as shown in FIG. 3 which is shorter than AB or A′B′, in other words, the minimum space distance between the ground down-leading wire and the lead, which determines the insulating intensity of the current lead during lightning, is shortened). Insulating intensity for bearing impact of lightning is enhanced. Furthermore, Since the route of the lightning flash over does not reach the cross arm metal member, burning to the composite insulator by power-flow current after lightning flash over is also prevented.

The upper metal cross arms 2 and the lower metal cross arms 4 also pull ad support the vertical ground down-leading wires 3, so that the ground down-leading wires 3 are not easy to bend when suffering impact from wind. The ground down-leading wires 3 preferably uses conductor of high intensity and not easy to deform. In order to make sure the ground down-leading wires 3 be not easy to deform, supporting insulating arms may be provided to separate and support the two ground down-leading wires 3 with the composite pole tower, as shown in FIG. 1 of the drawing.

Alternatively, two upper metal cross arms of a predetermined length are symmetrically extended from the ground wire cross arm 1 in a direction along the lead, and two ground down-leading wires are vertically leading down respectively so as to provide a splitting effect, as shown in FIG. 2 of the drawing.

When the ground down-leading wires 3 are connected to the pole tower via two lower metal cross arms 4 respectively, each of the ground down-leading wires is grounded along the tower body of the pole tower, wherein when the tower head of the pole tower is made of composite material and the rest portion the tower body is a metal pipe, the ground down-leading wire can be directly connected to the metal pipe via the lower metal cross arm 4 which is connected to the metal pipe, and thus the ground down-leading wire can be grounded to the earth via the metal pipe. Therefore, the ground down-leading wires are not vertically pulled out to be standing at a position above surface of the earth, so that inconvenience to daily life of people is prevented.

In a word, the method for grounding of the pole tower of composite pole tower of the present invention is simple and easy to achieve.

One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have been fully and effectively accomplished. It embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims. 

1. A method for vertically grounding and leading down form an inner side of a composite pole tower, wherein said method comprises the following steps: extending an upper metal cross arm from an extended line of at least one side of a ground wire cross arm which is made of metal and is positioned on top of said pole tower, vertically leading down a ground down-leading wire from a distal end of said upper metal cross arm, connecting said ground down-leading wire to said pole tower via a lower metal cross arm at a distance under a lower lead, and grounding said ground down-leading wire along a tower body of said pole tower, wherein when an lower portion of said tower body is a metal pipe, said ground down-leading wire is selectively directly connected to said metal pipe via said lower metal cross arm.
 2. The method, as recited in claim 1, two said upper metal cross arms are symmetrically extended from two sides of the ground wire cross arm respectively in a direction along said current lead thereof, wherein two ground down-leading wires are then vertically and symmetrically leaded down from.
 3. The method, as recited in claim 1, wherein said ground down-leading wires and said tower body are supported therebetween by at least an insulating arm.
 4. A composite pole tower which grounds from an inner side thereof, comprising: a tower body, a ground wire cross arm which is made of metal and is positioned on top of said pole tower, an upper metal cross arm extended from an extended line of at least one side of said ground wire cross arm, a ground down-leading wire vertically extended from a distal end of said upper metal cross arm, and a lower metal cross arm, wherein said ground down-leading wire is connected to said pole tower via said lower metal cross arm at a distance under a lower current lead of said pole tower, wherein said ground down-leading wire is grounded along said tower body of said pole tower, wherein when an lower portion of said tower body is a metal pipe, said ground down-leading wire is selectively directly connected to said metal pipe via said lower metal cross arm.
 5. The composite pole tower, as recited in claim 4, two said upper metal cross arms are symmetrically extended from two sides of the ground wire cross arm respectively in a direction along said current lead thereof, wherein two ground down-leading wires are then vertically and symmetrically leaded down.
 6. The composite pole tower, as recited in claim 4, wherein said ground down-leading wires and said tower body are supported therebetween by at least an insulating arm.
 7. The composite pole tower, as recited in claim 5, wherein said ground down-leading wires and said tower body are supported therebetween by at least an insulating arm. 